Process of making sprocket-wheels.



No. 637,655. Patented Hoy. 2l, |999.

N. E. PARISH.

PROCESS 0F MAKING SPHCKET WHEELS.

(Applinfion led Oct. 13, 1898.) CNO Model.)

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NITE-D STATES lPATENT muon.

NEFF E. PARISI-I, OF CLEVELAND, OHIO, ASSIGNOR TO THE PARISH d: BINGHAM COMPANY, OF SAME PLACE,

SPECIFICATION forming part of Letters Patent No. 637,655, dated November 21, 1899.

Application filed October 13, 1898. Serial No. 693,396. (No model `Wheels, of which the following is a specifica-V tion, the principle of the invention being herein explained and the best mode i-n which I have contemplated applying that principle,

so as to distinguish it from other inventions.V

My improved method of making bicycle sprocket-wheels by cold-pressing the metal into proper form offers many advantages over the hot-forging process-by giving a much denser product, the difference being especially increased at the surfacewhere hardness is most desired, and by giving a clean uniform surface free from scale and imperfections. This is of considerable importance in the subsequent treatment of the sprocket before nickf eling and causes a considerable saving in the cost of such treatment. Before the steel can be electroplated all of this scale must be removed and a chemically clean bright surface prepared. Where the sprocket-wheelshave been made by the cold-pressing process, this surface is clean, dense, and with few or no imperfections, and hence the cost of preparation for electroplating is much less than with those made by the usual process of hot-forging. The process of cold-pressing effects an important and advantageous difference in the chemical nature of the product made in this way over that made by hot-forging. When steel is heated for hot-forging, the sur-V face always burns to a greater or less degree, depending upon the length of time of heating, upon the temperature used, and upon the number of times it must be heated for each step in the process of shaping. This burn- `ing at the surface consists in a chemical union of the iron and carbon of the steel with the oxygen of the air, whereby the carbon passes off as gaseous oxids and the iron oXid Y remains on the surface as scale, which must be removed completely by grinding or pickling before the article can be electroplated. This burning during hot-forging often takes place to such an extent as to render the product brittle and to remove a large portion of the carbon of the steel, replacing it by oXid of iron or what the practical forger calls taking the life out of the metal. In consequence of this chemical action many defective sprocket-wheels are always produced by the method of hot-forging, and often the defect cannot be located until the wheel is used, thus causing serious loss to the makers of bicycles when such wheels must be replaced. In my cold-pressing process, the surface of the metal is not oxidized in the least and thus is not injured in any way. No scale is formed and no part of the carbon is removed. In the cold-pressing of sprocket-wheels there is not only no removal of carbon from the surface of the metal, but an advantageous chemical change takes place, whereby the surface is made harder. Carbon exists in steel in several different methods of chemical union. One such combination of carbon, causing the hardness of the steel to increase, is known as hardening-carbon and gives to steel the well-known effect of quenching or hardening. The cold-pressing of sprocket-wheels causes ythe carbon near the surface of the metal to change to this hardening condition, produc ing the effect of surface hardening, and at the same time leaving the interior metal tough. Cold-pressing also increases the rigidity and stiness of the metal and raises its elastic limit. All of these advantageous effects produced in cold-pressing over hotforging sprocket-wheels are intensified in the thinner part or web, because this part being small and thin is more liable to burn through and to become fatally weak by the reheating necessary for hot-forging, while in cold-pressing this part has the most of the hardeningcarbon and is hence strongest at these weaker points.

The annexed drawings and the following description set forth in detail one mode of carrying out the invention, such disclosed Inode constituting but one of various ways in which the principle of the invention may be used.

Referring to the drawings, Figure I is a plan view of a steel sprocket-blank before compression. Fig. II is a central sectional view of the web-compression dies. Fig. III is a central sectional view of the sprocket-blank IOO after being operated upon by said dies. Fig; IV is acentr'al sectional-view of the rim-compressing dies. Fig. V is a central sectional View through the sprocket-blank after it has been operated upon by the rim-compressing dies.

In carrying out my process a steel sprocketblank A of any suitable design is placed withont heating between two compressing-dies,'

faces d e, whereby the teeth are rounded off and the hardening-carbon in the rim,rand-par particularly in the wearngsurface of the teeth, is increased, but not to so great an eX- tent as in the web portion of the sprocketblank. The finished sprocket-blank F is now in its complete form, 'as shown in the drawings.

Fora more detailed description of the dies reference is hereby made to my pending applicationSerial No. 633,445.

Other modes of applying the principle of 3o my invention may' be employed instead of the one explained, change being made as regards the steps herein disclosed, provided the means covered by the following claim be employed. y

I vtherefore particularly point out and distinctly claim as my invention- Steps in a process of making steel sprocketwheels, consisting in cold-pressing the rim portion whereby oxidation of the metal is prevented, and cold-pressing the web portion to a greater degree than the rim portion whereby hardening-carbon is proportionally `increased in said web portion above the amount ofhardening-carbon in the rim portion, substantially as set forth.

Signed Vby me this 23d day of September,

NEFF E. PARISH.

Attest:`

D. T. DAvIEs, J. C. TURNER. 

